Not Applicable. This invention was conceived and developed with private funds.
Not Applicable.
The present invention relates to launch vehicles and, in particular, to recoverable booster stages that are used to assist orbital vehicles or payloads in attaining orbit or heading to outer space and to a method of recovering the booster stage for reuse.
Expendable launch vehicles of multiple stages are widely used to propel space vehicles or payloads into space. Recovery of the first stage, or booster stage, is impossible or impractical with the existing systems and method of operation. The only reusable launch vehicle is the Space Shuttle, which is too costly to be competitive for commercial launches. Commercial launches are competitively sold based on launch price, payload lift capability, demonstrated reliability, launch availability, and finance terms. A reusable launch vehicle is commercially viable only if it offers significant benefits over an expendable launch vehicle in one or more of these areas. While there are many concepts for reusable launch vehicles in the prior art, none have been commercially viable.
Steven J. Isakowitz, xe2x80x9cInternational Reference Guide to Space Launch Systemsxe2x80x9d, American Institute of Aeronautics and Astronautics, 1991, 295 pages.
Jefferson Morris, xe2x80x9cNew Expendable Rocket Needed to Supplement EELV, Teets Saysxe2x80x9d, Aerospace Daily, Feb. 21, 2003, 1 page.
An object of the present invention is to significantly reduce the cost of launching payloads into space, increase reliability, and increase availability while providing a payload lift capability near that of existing expendable launch vehicles. Another object is to enable a booster stage to land in a reusable condition at any desired site, particularly at or near the launch site, thereby eliminating the need, time and costs to transport the booster back to the launch site and permitting a rapid turnaround time between flights.
The foregoing objects are attained, in accordance with the present invention, by a recoverable/reusable booster stage having a liquid-fueled air breathing engine or engines side-mounted symmetrically around the central portion of a booster of conventional configuration in alignment with the center axis of the body and of sufficient thrust to hover the spent weight of the booster on jet thrust alone in a vertical tail-down orientation. In a particular embodiment, two jet engines are mounted symmetrically on opposite sides of the inter-tank spacer of a conventional expendable booster stage in general alignment with the central axis of the booster. After launch and separation from the 2nd stage/payload the booster returns to the launch site under jet power and lands vertically, tail down, hovering over the landing pad on jet thrust. Landing gear and low speed wings are not required, which greatly enhances the payload lift capability for the booster. In another embodiment, the jet engines also run on ascent augmenting the booster""s rocket thrust. The net positive thrust from the jet engines prevents the loss in performance from the added weight to the booster and allows the booster to carry more rocket propellant, i.e. to impart a greater delta-velocity to the 2nd stage/payload. This produces a payload lift capacity near that of an expendable launch vehicle. Together and in part, these embodiments lower the costs to launch payloads into space since the booster is recovered and reused after each launch.
The present invention provides the following advantages. (1) A payload lift capability near that of a comparable expendable launch vehicle. (2) Greater safety than horizontal landing concepts, which involve much higher landing speeds than this invention and have a greater potential for causing damage during a crash. (3) Low cost development since the preferred embodiment can be constructed from currently available boosters and technology, which avoids the cost of developing a new design. (4) Lower operating costs by consolidating launch operations around a single booster, i.e. launching large and small payloads with a common booster. Smaller payloads are launched by off-loading booster propellant and throttling the main engines. This limits the acceleration load on the payload. (5) Greater availability and flight rate flexibility since this invention is recovered and refurbished for flight at the launch site. (6) Greater reliability than expendable launch vehicles since this invention facilitates post-flight inspections. Design margins and reliability in later practice of this invention are improved as the flight environment data is correlated with the observed fatigue.